The human meteorite
A flood of new evidence has revolutionized the way we look at our
BOSTON — You've got to hand it to geophysicists. They began this century studying the third rock from the sun. Now, they're exploring the entire solar system.
Earth science has become planetary science. Meteorologists probe alien atmospheres for clues to our own weather and climate. The quest to learn how life evolved extends to Mars. The naive vision of Earth orbiting serenely through empty space is gone. We are learning to live in a rough neighborhood permeated by disruptive magnetic fields and speeding solar particles as well as wandering asteroids.
But there's more to geoscience than adventurous discovery. It thrives in that messy zone where science, technology, and public policy meet to advance the common good. A century ago, hurricanes caught people off-guard, earthquakes rattled for little apparent reason, and volcanoes often erupted without warning. While Earth scientists still have much to learn about our planet's phenomena, they now understand enough to warn of their dangers and help communities prepare for trouble. The 20th century is leaving us significantly less at the mercy of such natural forces - and of an irrational fatalism concerning them - than we used to be.
Oceanographer Richard Barber at the Duke University Marine Laboratory in Beaufort, N.C., reflected this vision in commenting on scientists' growing ability to forecast El Nio and its effects. El Nio warms the equatorial Pacific and influences weather globally. Although their skill still is far from perfect, climate teams can often forecast El Nio's weather disruptions many months in advance. Such warnings help people prepare to meet the local threat.
Dr. Barber says, "The economic benefits of El Nio forecasting are nothing compared to the social benefits." He explains that such forecasts "give people the realization that the natural climate forces are understandable. It gives people more confidence. They know it isn't supernatural."
Such knowledge brings new responsibilities. People must use it wisely to gain its benefits. And geoscientists need to open their thought to new perspectives, including nonscientists' viewpoints. What probably is the greatest geophysical discovery of this century - discovery of the underlying mechanism that shapes Earth's surface - makes the point.
From 1912 to his death in 1930, German meteorologist Alfred Wegener was a geologist's hair shirt. He promoted the heretical notion that continents whose outlines fit together once were together. Geologists thought they knew better. They believed Earth's surface is shaped by wrinkling as the planet slowly cools down and shrinks. Continents could move up or down, but not sideways. Wegener integrated knowledge from several fields, including paleobiology, at a time when those fields were segregated. Their practitioners rarely interacted. Meteorologist Wegener was treading on forbidden turf. Feelings ran so strong that, 50 years ago, the professor of my geomorphology class described Wegenerism as "a great evil." But a decade later, Roger Revelle - then director of the Scripps Institution of Oceanography in La Jolla, Calif. - remarked that "we no longer have to talk about [continental drift] in the washroom."
A flood of new evidence revolutionized geoscientists' concept of Earth. It revealed Earth's crust to be a collection of plates that bump together, rub together, or overlap. New crust wells up along plate boundaries at ocean ridges and moves away carrying continents with it. Old ocean crust plunges back down beneath other plate boundaries along continental edges. There the crustal material is often recycled and returned to the surface and the atmosphere through volcanoes. This incessant action causes most earthquakes and many volcanoes.
What scientists call plate tectonics now provides an overarching perspective for Earth science. It guides research into earthquake and volcano mechanisms. It provides a framework for fields as diverse as global climate change and the ecology of a mountain range. Seismologists can't predict when an earthquake will hit. But knowing where plates interact and form fault lines, they can warn of vulnerability. Climatologists know that recycling of ocean crust and sediments - including carbon sequestered from atmospheric carbon dioxide - influences the composition of the atmosphere. Ecologists can better understand habitats in the Canadian Rockies when they know how these mountains crumpled up as two plates crunched together.
However, knowledge is only as beneficial as people make it. It did little good for seismologists to warn of Turkey's earthquake risk when building codes weren't enforced and people refused to leave high-risk areas. As Donald Swanson at the US Geological Survey's Hawaii Volcano Observatory has observed, "When you mesh natural hazards with politics, economics, development, etc., it's a recipe from which it's hard to make an edible dish."
Volcanologist Michael Sheridan with the State University of New York at Buffalo says the way to make it palatable is to combine public education with local monitoring. He says, for example, people "should know their volcano ... and identify safe areas." When Mt. Pinatubo erupted in the Philippines in 1992, such preparation was what Dr. Sheridan calls "the key to mitigation."
A decade of such cooperative planning also worked for Papua, New Guinea, when Mt. Rabaul erupted in 1994. Twelve people died, as opposed to 500 in the 1937 eruptions.
Such successes are relatively rare, though. Fouad Bendimerod at RMS Inc. in Menlo Park, Calif., and several colleagues writing in Science International warn that "the rate of urban risk caused by explosive population growth far exceeds the progress made in preparedness," especially in developing countries. The authors are part of an international scientific organization called the Earthquakes and Megacities Initiative, which is trying to speed up the needed preparedness.
Citing United Nations statistics, Dr. Bendimerod and colleagues note that 80 percent of our planet's human population is crowding into 3 percent of the land. Many people are jamming into megacities in areas vulnerable to floods, severe storms, and earthquakes. Focusing on quakes, they estimate that every dollar spent on preparedness saves, on average, $10 in disaster recovery costs.
To gain such a benefit, geoscientists have to work as part of a human community in which other players have different agendas and perspectives. Moreover, the scientists have to work with each other. Geologists, seismologists, volcanologists, meteorologists, oceanographers, biologists all need one another's insights to fully understand the natural processes of our planet. That is why they are taking down the intellectual walls that separated their special interests a hundred years ago. Those interests now are merging into the new overarching field of planetary system science. As Charles Kennel, director of Scripps Institution of Oceanography, puts it: "We are about to cross the threshold into an extraordinary age of scientific research - global change research. We are about to kick this [science] to a new level."
Wegener, despised by specialists a half century ago, would finally seem to have the last word. In the foreword of the final (1929) version of his book on drifting continents, he observed: "It is only by combining the information furnished by all the earth sciences that we can hope to determine 'truth.' "
(c) Copyright 1999. The Christian Science Publishing Society